1. Field of the Invention
The present invention relates to heel-retaining devices for ski bindings, of the type in which the heel-holding member is carried by a rotary plate located beneath the heel of the ski boot.
2. Description of the Prior Art
In the so-called pivoted heel-retaining devices of the type mentioned above, the heel-holding member is usually mounted on a stirrup member which surrounds the heel of the ski boot and the side arms of which are pivotally mounted on flanges carried by each side of the rotary plate. The advantage of these heel-retaining devices lies in the fact that they permit pivotal displacement of the ski boot about a vertical axis located substantially opposite to the skier's tibia when a high torsional stress is developed and when a tripping action is produced on the safety toe-abutment member associated with the heel-retaining device in order to release the ski boot.
In order to provide an equal degree of safety in the event of a forward fall of the skier, the heel-holding member is so designed as to release the ski-boot heel automatically in the event that an unduly large external stress is exerted on the skier's leg. It is readily apparent that, when combined extension and torsion forces arise, the two retaining devices of the ski binding (namely the toe-abutment device and heel-holding member) are both urged towards their boot-releasing position whilst the rotary plate of the heel-retaining device is caused to undergo a pivotal displacement under the action of the torsional stress exerted on the skier's foot.
By reason of the advantages attached to this design concept, it has already been proposed to associate a heel-retaining device of the aforementioned type with the ski-brake device usually provided for stopping a ski as soon as a ski boot has been completely released from the ski. In some designs already proposed, the ski brake is simply associated with the corresponding heel-retaining device whereas in other designs, the ski brake is completely integrated with said device.
Thus FIGS. 6 to 9 of French Pat. No. FR-2,278,363 illustrate the association of a pivoted heel-retaining device and a ski-brake device which is mounted behind the rotary plate of said heel-retaining device in order to be controlled by the boot-engagement support of said device. In this form of construction, there is therefore no integration of the ski brake in the pivot of the heel-retaining device, thus resulting in an increase in overall size of the assembly. Furthermore, the control of the ski brake by means of the boot-engagement support of the heel-retaining device is subject to many disadvantages such as the attendant danger of ski-brake release while skiing is in progress, and unreliability of brake control by reason of the elasticity of the heel-retaining device. In addition, certain components of the ski-brake device are liable to interfere with rotational movement of the rotary plate of the heel-retaining device under certain circumstances. It is in fact extremely doubtful whether the assembly in accordance with this design is really capable of operating.
French Pat. No. FR-2,453,606 describes two different forms of construction of a pivot-type heel-retaining device associated with a ski brake. In one embodiment (shown in FIGS. 18 to 21), the brake is stationarily fixed and placed behind the pivot, the brake-operating pedal being placed above the rotary plate of the pivot in the position of readiness. Under these conditions, at the time of boot disengagement under simple torsional stress, one of the lateral flanges of the rotary plate moves very rapidly into a position of abutting contact with the brake-operating pedal. This has the effect of abruptly stopping the rotation of the pivot with all the disadvantages which this is liable to entail.
In the other form of construction described in the cited patent (with reference to FIGS. 1 to 17), the ski brake is mounted on the rotary plate of the pivot. But after a boot disengagement under torsional stress which has caused a rotational displacement of the pivot-plate, operation of the ski brake is wholly unpredictable. Moreover, in the event of a complex fall which has initially resulted in lifting of the ski-boot heel, the upward displacement of the brake pedal permits free rotation of the pivot. The system in accordance with this design is also delicate since the ski brake is carried by the pivot-plate and rotates with this latter. Should one of the braking arms be deformed, however, rotation of the pivot would be hindered or even prevented.
The German patent specification No. DE-A 2,906,726 also describes a pivoted heel-retaining device in which a fixed ski-brake is incorporated in the rotary plate. However, rotational displacement of the pivot is possible only over a very limited range of angular travel when the ski brake is in the standby position. This accordingly prevents the pivot from performing its normal function.
The same remark applies to the forms of construction described in the French patent specification Nos. FR-A 2,500,314 and FR-A 2,511,258.